Electro-optical device and electronic apparatus

ABSTRACT

An electro-optical device includes a first light shielding film; a transistor element formed on the first light shielding film to overlap the first light shielding film; a second light shielding film formed on the transistor element to overlap the transistor element and electrically connected to an input terminal of the transistor element; a transparent conductive film extended toward an upper layer side of the second light shielding film in an opening region, through which light penetrates, of the display region; a dielectric film formed on the transparent conductive film in the opening region; and a transparent pixel electrode formed on the dielectric film in the opening region, constituting a storage capacitor together with the transparent conductive film and the dielectric film, and having a transparent pixel electrode which is electrically connected to the transistor element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/652,277, filed Jan. 5, 2010, which claims priority to Japanese PatentApplication No. 2009-000277, filed Jan. 5, 2009 and Japanese PatentApplication No. 2009-259898, filed Nov. 13, 2009. The foregoingapplications are incorporated herein.

BACKGROUND

1. Technical Field

The present invention relates to an electro-optical device includingthin film transistors which are disposed for every pixel on an elementsubstrate as a switching element, such as a liquid crystal device, andan electronic apparatus including the electro-optical device, such as aliquid crystal projector.

2. Related Art

Such an electro-optical device includes pixel electrodes, scanning linesfor selectively driving the pixel electrodes, data lines and a TFT (ThinFilm Transistor) as a pixel switching element, which are provided on asubstrate, to deliver the active matrix drive. In the active matrixdrive, image display is implemented by supplying a scanning signal tothe scanning lines to control the operation of the TFT, andsimultaneously supplying the image signal to the data lines at thetiming that the TFT is driven to be ON. In such an electro-opticaldevice, a storage capacitor is provided between the TFT and a pixelelectrode made of a transparent electrode such as an ITO for the purposeof enhancing contrast in the displayed image. Further, a light shieldinglayer may be provided for the purpose of shielding from light elementssuch as the pixel switching TFT installed corresponding to each pixel(e.g., see JP-A-7333651, JP-A-10-10579 and JP-A-2001-56485).

However, when the liquid crystal device is operated, the storagecapacitor sustaining the potential of the pixel electrode according tothe image signal during a predetermined period is formed in a region,though which light does not penetrate, of the display region, and in anon-opening region in which various wiring such as data lines andscanning lines is provided. Therefore, there is a tradeoff in therelationship between the enlarged opening region of the plurality ofpixels which constitute the display region, through which the light maysubstantially penetrate, and the enlarged size of the storage capacitor.

Accordingly, it is technically difficult to simultaneously increase thecapacitance value of the storage capacitor and size of the openingregion, and thus there is a technical problem in enhancing the displayperformance of an electro-optical device such as a liquid crystaldevice.

SUMMARY

An advantage of some aspects of the invention is that it provides anelectro-optical device which can enhance display performance thereof bysimultaneously implementing an increased capacitance value of a storagecapacitor and an enlarged size of an opening region, and an electronicapparatus including the electro-optical device.

According to a first aspect of the invention, there is provided anelectro-optical device including: a first light shielding filmconstituting a portion of a display region on a substrate and formed ina non-opening region through which light does not penetrate; atransistor element formed on the first light shielding film to overlapthe first light shielding film; a second light shielding film formed onthe transistor element to overlap the transistor element andelectrically connected to the transistor element; a transparentconductive film formed on the second light shielding film and formed atleast in an opening region through which light penetrates; a dielectricfilm formed on the transparent conductive film in the opening region;and a transparent pixel electrode formed on the dielectric film in theopening region, constituting a storage capacitor together with thetransparent conductive film and the dielectric film, and having atransparent pixel electrode which is electrically connected to thetransistor element.

With the first electro-optical device of the invention, on thesubstrate, wiring, such as scanning lines and data lines, and transistorelements are disposed across an insulation film to electrically insulateeach other, and are stacked, if necessary, to form a circuit for drivingthe pixel electrode. A pixel electrode is disposed on an upper layerside. Since each of the scanning lines, the data lines and the pixelswitching transistor elements includes opaque constituent elements suchas a semiconductor layer and a metal film, it is formed in thenon-opening region of the display region on the substrate, through whichlight does not penetrate, without affecting the image display by theelectro-optical device.

The first light shielding film constitutes a portion of the displayregion on the substrate, and is formed in the non-opening region throughwhich the light does not penetrate. Consequently, the first lightshielding film can shield the light incident upon the transistor elementfrom the lower side of the transistor element. In this instance, thenon-opening region is defined by an element having a light shieldingproperty of the constituent elements which constitute theelectro-optical device, the element including the first light shieldingfilm.

The transistor element is formed on the first light shielding film tooverlap the first light shielding film. At the time of operation of theelectro-optical device, the transistor element serves as a controlelement since it is turned ON or OFF in response to, for example, ascanning signal supplied to a gate via the scanning line to controlsupply or non-supply of the image signal to the pixel electrode.

Since the second light shielding film is formed on the transistorelement to overlap the transistor element, it can shield the transistorelement from the light at its upper portion side. The second lightshielding film is electrically connected to the transistor element. Thesecond light shielding film is electrically connected to, for example,the source of the transistor element, and constitutes a portion of thedata line supplying the image signal.

The transparent conductive film is made of a transparent conductivematerial such as ITO, and is extended toward the upper layer side of thesecond light shielding film in the opening region of the display region,through which the light penetrates.

The dielectric film is, for example, a transparent film formed on thetransparent conductive film in the opening region. It is preferable thatthe dielectric film is formed to have a thin thickness by using amaterial having a high dielectric constant in order to increase thecapacitance value which will be described below.

The pixel electrode is formed on the dielectric film in the openingregion, and constitutes the storage capacitor together with thetransparent conductive film and the dielectric film. The pixel electrodeis a transparent film electrically connected to the transistor element,and is made of a transparent conductive material such as ITO, similar tothe transparent conductive film.

According to the first electro-optical device of the invention, sincethe storage capacitor is formed in the opening region, it is able toincrease the capacitance value as compared with a case in which thestorage capacitor is formed only in the non-opening region. In addition,since the storage capacitor is formed of a transparent film, the openingratio which is a ratio of the opening region occupying the pixel is notlowered, without narrowing the opening region.

Consequently, according to the first electro-optical device of theinvention, the capacitance value of the storage capacitor is increased,and the size of the opening region is enlarged, thereby enhancing thedisplay performance of the electro-optical device.

According to the first electro-optical device of the invention, thetransparent conductive film has an aperture portion which is formed bypartially opening the transparent conductive film in the opening region.A transparent connection portion is extended along the thicknessdirection of the substrate in the aperture portion, and electricallyconnects the output terminal and the pixel electrode.

With the invention, while it maximally takes a size of the transparentconductive film constituting one side of a pair of the capacitorelectrodes which is a portion of the storage capacitor, an electricconnection between the pixel electrode and the output terminal via theconnection can be achieved.

According to other aspect of the first electro-optical device of theinvention, the electro-optical device includes a relay layer extendedtoward an upper layer side of the transistor element so as to overlapthe transistor element, shielding the transistor element together withthe second light shielding film from light, and electrically relayingthe transistor element and the pixel electrode.

With the embodiment of the invention, the transistor element can beshielded from the light by both sides of the second light shielding filmand the relay layer. Consequently, at the time of operation of theelectro-optical device, it is able to reduce light leakage currentoccurring in the transistor element.

According to other aspect of the first electro-optical device of theinvention, the dielectric film may be made of alumina.

With the embodiment of the invention, since the alumina has a dielectricconstant relatively higher than other dielectric material, it is able toincrease the installable capacitance value in the cases where the sizeof the storage capacitor is constant.

According to another aspect of the invention, there is provided ansecond electro-optical device including: a transistor element; a lightshielding film placed on the transistor element to overlap thetransistor element, and electrically connected to the transistorelement; a transparent conductive film placed on the light shieldingfilm and having an aperture portion which is formed over two adjacentpixels; a transparent pixel electrode formed opposite to the transparentconductive film across the dielectric film to constitute a storagecapacitor, and electrically connected to the transistor element; a firstrelay layer being the same layer as the transparent conductive film,placed inside the aperture portion when seen in a plan view, andelectrically connecting the pixel electrode and the transistor element;and a second relay layer of an island shape placed on the same layer asthe light shielding film, and electrically connecting the pixelelectrode and the transistor element.

With the second electro-optical device of the invention, on thesubstrate, wiring, such as scanning lines and data lines, and transistorelements are disposed across an insulation film to electrically insulateeach other, and are stacked, if necessary, to form a circuit for drivingthe pixel electrode. A pixel electrode is disposed on the upper layerside. Since each of the scanning lines, the data lines and the pixelswitching transistor elements includes opaque constituent elements suchas a semiconductor layer and a metal film, it is formed in thenon-opening region of the display region on the substrate, through whichlight does not penetrate, without affecting the image display by theelectro-optical device.

At the time of operation of the electro-optical device, the transistorelement severs as a control element since it is turned ON or OFF inresponse to, for example, a scanning signal supplied to a gate via thescanning line to control supply or non-supply of the image signal to thepixel electrode.

Since the light shielding film is formed on the transistor element tooverlap the transistor element, it can shield the transistor elementfrom the light at its upper portion side. The light shielding film iselectrically connected to the transistor element. The light shieldingfilm is electrically connected to, for example, the source of thetransistor element, and constitutes a portion of the data line supplyingthe image signal.

The transparent conductive film is made of a transparent conductivematerial such as ITO, and is extended toward the upper layer side of thelight shielding film in the opening region of the display region,through which the light penetrates.

The dielectric film is, for example, a transparent film formed on thetransparent conductive film in the opening region. It is preferable thatthe dielectric film is formed to have a thin thickness by using amaterial having a high dielectric constant in order to increase thecapacitance value which will be described below.

The pixel electrode is formed on the dielectric film in the openingregion, and constitutes the storage capacitor together with thetransparent conductive film and the dielectric film. The pixel electrodeis a transparent film electrically connected to the transistor element,and is made of a transparent conductive material such as ITO, similar tothe transparent conductive film.

The first relay layer is provided on the same layer as the transparentconductive film (i.e., a layer between the pixel electrode and thetransistor element). In this instance, the term “same layer” means alayer formed by the same film growing method as the transparentconductive film. The first relay layer is electrically disconnected fromthe transparent conductive film, and is provided to electrically connectthe pixel electrode and the transistor element. More specifically, thefirst relay layer is electrically connected to, for example, an outputterminal side of the transistor of a lower layer side via the contacthole, and is also electrically connected to the pixel electrode of theupper layer side. By providing the first relay layer, the electricalcommunication between the transistor element and the pixel electrode canbe preferably achieved.

The second relay layer is placed in the island shape on the same layeras the light shielding film, and electrically connects the pixelelectrode and the transistor element. In this instance, the term “samelayer” means a layer formed by the same film growing method as the lightshielding film. The second relay layer is electrically disconnected fromthe light shielding film, and is provided to electrically connect thepixel electrode and the transistor element. More specifically, thesecond relay layer is electrically connected to, for example, an outputterminal side of the transistor of a lower layer side via the contacthole, and is also electrically connected to the pixel electrode of theupper layer side. By providing the second relay layer, the electricalcommunication between the transistor element and the pixel electrode canbe preferably achieved.

According to the second electro-optical device of the invention, sincethe storage capacitor is formed in the opening region, it is able toincrease the capacitance value as compared with the case in which thestorage capacitor is formed only in the non-opening region. In addition,since the storage capacitor is formed of a transparent film, a openingratio which is a ratio of the opening region occupying the pixel is notlowered, without narrowing the opening region.

According to the second electro-optical device of the invention, thetransparent conductive film has an aperture portion which is extended tooverlap either side of two adjacent pixels, and the pixel electrode isprovided to at least partially overlap the aperture portion of thetransparent conductive film. Further, the transparent conductive film iselectrically connected to the transistor element via the first relaylayer which is formed in the aperture portion. In this way, the pixelelectrode and the transistor element can be electrically connected toeach other via the aperture portion of the transparent conductive film,and since the relay layer is transparent, it is able to preventreduction of an opening efficiency.

Consequently, according to the second electro-optical device of theinvention, the capacitance value of the storage capacitor is increased,and the size of the opening region is enlarged, thereby enhancing thedisplay performance of the second electro-optical device.

According to second electro-optical device of the invention, the firstrelay layer has a longer length of a first direction, along which asemiconductor layer of the transistor element is extended, than that ofthe second relay layer.

With the embodiment of the invention, the first relay layer protrudestoward the pixel electrode side, rather than the second relay layerwhich is provided in the island shape on the same layer as the lightshielding film, it is able to promote the electrical connection of thetransistor element by passing through the first transparent relay layer,while preventing reduction of the opening ratio.

According to the other embodiment of the second electro-optical deviceof the invention, the second electro-optical device further includes acapacitor separation film placed on a layer upper than the transparentconductive film and on a layer lower than the pixel electrode, andseparating the storage capacitor between adjacent pixels.

With the embodiment of the invention, since the storage capacitorbetween the adjacent pixels is separated by the capacitor separationfilm, it is preferable that the quality of the display image can beenhanced. Further, it is able to adjust the size of the storagecapacitor by adjusting the area of the capacitor separation film.

According to the other embodiment of the second electro-optical deviceof the invention, the aperture portion of the transparent conductivefilm is provided between the adjacent light shielding films. Thecapacitor separation film has capacitor separation film apertureportions inside the pixel electrode when seen in a plan view and acapacitor separation film aperture portion between the aperture portionand the adjacent light shielding film in a direction intersecting withan extending direction of the light shielding film. The storagecapacitor has a shape corresponding with the capacitor separation filmaperture portion.

With the embodiment of the invention, the capacitor separation film hasa capacitor separation film aperture portion between the light shieldingfilm and the aperture portion of the capacitor electrode, and thestorage capacitor is formed corresponding to the shape thereof.Therefore, with the area of capacitor electrode and the pixel electrodebeing disposed in opposition, the planar area of the storage capacitorregion is secured to be as wide as possible.

According to the electro-optical device of the invention, the secondelectro-optical device further includes a third relay layer provided ona layer between the transistor element and the light shielding film, andelectrically relay connecting the transistor element and the pixelelectrode. The third relay layer has a body portion extending in asecond direction intercrossing with a first direction along which asemiconductor layer of the transistor element is extended, and aprotrusion portion protruding from the body portion in the firstdirection, the third relay layer is disposed to cover a portion of achannel portion of the transistor element and an electrode, which iselectrically connected to the pixel electrode, of electrodes on bothsides of the channel portion of the transistor element.

With the embodiment of the invention, the third relay layer relays theelectrical connection between the transistor element and the pixelelectrode, and is provided to cover and shield one of two electrodesinterposed between the channel portion in the transistor element, thatis, one of source and drain electrodes which is electrically connectedto the pixel electrode, and a portion of the channel portion, therebypreventing the light leakage in the transistor element, that is,generation of the current due to light touch. In particular, it iseffective that an LDD region between the electrode connected to thepixel electrode and the channel portion is shielded.

According to the other aspect of the invention, there is provided anelectronic apparatus including the electro-optical device describedabove.

According to the electronic apparatus of the invention, the electronicapparatus includes the electro-optical device described above, it canimplement various other electronic apparatuses which is capable ofperforming the display of high quality, such as projection displaydevices, cellular phones, electronic notebooks, word processors,view-finders or monitor-direct-viewing video tape recorders,workstations, video phones, point-of-sale (POS) terminals, orapparatuses having touch panels. Further, as the electronic apparatus ofthe invention, an electrophoresis device such as electronic paper can beimplemented.

Other operations and advantages of the invention will become apparentfrom the following description of the embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view showing the overall configuration of a liquidcrystal device according to an embodiment.

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1.

FIG. 3 is a circuit diagram showing the electric configuration of theliquid crystal device according to the embodiment.

FIG. 4 is a diagram transparently showing a position relationship, suchas wiring, in an image display region in the liquid crystal deviceaccording to the embodiment.

FIG. 5 is a plan view showing layout of the respective constituentelements on one layer of different layers in the liquid crystal deviceaccording to the embodiment.

FIG. 6 is a plan view showing layout of the respective constituentelements on the other layer of different layers in the liquid crystaldevice according to the embodiment.

FIG. 7 is a cross-sectional view taken along a line VII-VII in FIGS. 4to 6.

FIG. 8 is a partial cross-sectional view showing a liquid crystal deviceaccording to a modified example.

FIG. 9 is a plan view transparently showing a position relationship ofthe respective layers constituting a liquid crystal device according toa second embodiment.

FIG. 10 is a plan view transparently showing a position relationship ofthe respective layers constituting a liquid crystal device according toa second embodiment.

FIG. 11 is a cross-sectional view showing a laminate structure of theliquid crystal device according to the second embodiment.

FIG. 12 is a plan view showing the configuration of a projector which isan example of an electronic device to which an electro-optical deviceaccording to the embodiment is applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Now, an embodiment of an electro-optical device and an electronicapparatus according to the invention will be described with reference tothe drawings. As an example of the electro-optical device according tothe invention, this embodiment relates to a liquid crystal deviceemploying a TFT active-matrix driving method.

1: Liquid Crystal Device First Embodiment 1-1: Overall Configuration ofLiquid Crystal Device

First, the overall configuration of a liquid crystal device 1 accordingto this embodiment will be described with reference to FIGS. 1 and 2.

FIG. 1 is a plan view showing the overall configuration of the liquidcrystal device 1 according to this embodiment. FIG. 2 is across-sectional view taken along a line II-II in FIG. 1.

Referring to FIGS. 1 and 2, the liquid crystal device 1 includes aTFT-array substrate 10 and an opposing substrate 20 which are disposedopposite to each other. The TFT-array substrate 10 is an example of asubstrate according to the invention. The TFT-array substrate 10 is, forexample, a transparent substrate such as a quartz substrate or a glasssubstrate, or a silicon substrate. The opposing substrate 20 is asubstrate made of, for example, the same material as the TFT-arraysubstrate 10. Between the TFT-array substrate 10 and the opposingsubstrate 20, liquid crystal is encapsulated to form a liquid crystallayer 50. The TFT-array substrate 10 and the opposing substrate 20 arebonded with each other via a sealing member 52 provided in a sealingregion which is placed around an image display region 10 a, in whichelectro-optical operation is carried out. The image display region 10 ais an example of a “display region” in the invention.

The sealing member 52 is composed of an ultraviolet curing resin, athermosetting resin, or the like for bonding the TFT-array substrate 10and the opposing substrate 20 with each other. The sealing member 52 isformed by applying such a material onto the TFT-array substrate 10 andcuring the material by ultraviolet irradiation, heating, or the like ina manufacturing process. Further, for example, in the sealing member 52,a gap member 56 composed of glass fibers or glass beads are dispersed sothat a gap of a predetermined value is provided between the TFT-arraysubstrate 10 and the opposing substrate 20 (i.e., an inter-substrategap).

Inside and in parallel to the sealing region in which the sealing member52 is disposed, a frame-shaped light shielding film 53 having a lightshielding property which defines a frame region of the image displayregion 10 a is provided on the opposing substrate 20. Alternatively, theframe-shaped light shielding film 53 may be formed entirely or partiallyon the TFT-array substrate 10 as an internal light shielding film.

In a peripheral region located around the image display region 10 a onthe TFT-array substrate 10, a data-line driving circuit 101, a samplingcircuit 7, scanning-line driving circuits 104, and external-circuitconnecting terminals 102 are respectively provided.

In the peripheral region on the TFT-array substrate 10, the data-linedriving circuits 101 and the plurality of external-circuit connectingterminals 102 are provided along one edge of the TFT-array substrate 10in a region located outside the sealing region.

Furthermore, in the region inside the sealing region of neighboringregions on the TFT array substrate 10, the sampling circuit 7 isprovided along one side of the image display region 10 a which is alongone side of the TFT-array substrate 10, and is covered by theframe-shaped light shielding film 53.

In addition, the scanning-line driving circuits 104 are provided alongtwo edges of the TFT-array substrate 10 adjacent to the one edgethereof, and are covered by the frame-shaped light shielding film 53.Further, in order to electrically interconnect the two scanning-linedriving circuits 104 provided on both sides of the image display region10 a, a plurality of wiring 105 are provided along the remaining oneedge of the TFT-array substrate 10, and is covered by the frame-shapedlight shielding film 53.

In the peripheral regions on the TFT-array substrate 10,vertical-conduction terminals 106 are provided in the regions facing aportion of four corners on the opposing substrate 20, andvertical-conduction members are provided between the TFT-array substrate10 and the opposing substrate 20 and are electrically connected to thevertical-conduction terminals 106 corresponding to thevertical-conduction terminals 106.

Referring to FIG. 2, a laminate structure including TFTs for pixelswitching or wiring such as scanning lines, data lines or the like isformed on the TFT-array substrate 10. In the image display region 10 a,a pixel electrode 9 is provided in a matrix shape on the pixel switchingTFT or the wiring such as scanning lines, data lines or the like. Thepixel electrode 9 is formed of a transparent electrode made of an ITOfilm. An alignment film 16 is formed on the pixel electrode 9.

On the opposing substrate 20, a light shielding film 23 is provided onthe surface opposite to the TFT-array substrate 10. The light shieldingfilm 23 is made of, for example, a light shielding metal film, and ispatterned, for example, in a grid shape in the image display region 10 aon the opposing substrate 20. An opposing electrode 21 made of an ITOfilm is provided, for example, as a solid opposite to the plurality ofpixel electrodes 9 on the light shielding film 23 (lower than the lightshielding film 23 in FIG. 2), and an alignment film 22 is furtherprovided on the opposing electrode 21 (lower than the opposing electrode21 in FIG. 2).

The liquid crystal layer 50 is composed of, for example, one type ofnematic liquid crystal or a combination of more than one type of nematicliquid crystal, and exhibits a predetermined orientation between thepair of alignment films. If the liquid crystal device is driven, thepixel electrodes 9 and the opposing electrodes 21 are applied by voltageto form a liquid crystal holding capacitance between the pixelelectrodes 9 and the opposing electrodes 21.

In this instance, although now shown herein, in addition to thedata-line driving circuit 101 and the scanning-line driving circuits104, a precharging circuit that supplies precharging signals level toplural data lines before a testing circuit for testing the like of theliquid crystal device at a predetermined voltage image signals aresupplied, quality, defects, or the during manufacturing or at the timeof shipping, and so forth may be provided on the TFT-array substrate 10.

1-2: Electric Configuration of Liquid Crystal Device

Next, the electrical configuration in the image display region 10 a ofthe liquid crystal device 1 will be described with reference to FIG. 3.FIG. 3 is an equivalent circuit diagram of various elements, wiring andso forth in a plurality of pixels arranged in a matrix shape toconstitute the image display region 10 a of the liquid crystal device 1according to this embodiment.

Referring to FIG. 3, at each of the plurality of pixels arranged in thematrix shape to constitute the image display region 10 a, the pixelelectrode 9 and the TFT 30 which is an example of a “transistor element”in the invention are provided. The TFT 30 is electrically connected tothe pixel electrode The TFT 30 controls switching of the pixel electrode9 so as to switch supply and non-supply of an image signal to the pixelelectrode 9 during operation of the liquid crystal device 1. A data line6, through which the image signal is supplied, is electrically connectedto the source region of the TFT 30. Image signals Si, S2, . . . , Snwritten to the data lines 6 may be supplied sequentially line by line inthis order, or in groups to sets of adjacent data lines 6.

The gate of the TFT 30 is electrically connected to a scanning line 11.The liquid crystal device 1 is configured so that pulses of scanningsignals G1, G2, . . . , Gm are applied to the scanning lines 11sequentially in this order at specific timings. The pixel electrode 9 iselectrically connected to the drain of the TFT 30, and the TFT 30serving as a switching element is turned off for a predetermined period,so that the image signals Si, S2, Sn supplied from the data lines 6 arewritten at specific timings. The image signals Si, S2, . . . , Sn havingcertain levels which are written to the liquid crystal via the pixelelectrodes 9 are maintained for a predetermined period between the pixelelectrodes 9 and the opposing electrode 21 (see FIG. 2) formed on theopposing substrate 20 (see FIG. 2).

The liquid crystal constituting the liquid crystal layer 50 (see FIG. 2)changes the orientation or order of its molecules according to thelevels of voltages applied thereto, thereby modulating light to achievemulti-level display. In a normally white mode, the transmittance ofincident light decreases in accordance with voltages applied to theindividual pixels. On the other hand, in a normally black mode, thetransmittance of incident light increases in accordance with voltagesapplied to the individual pixels. Thus, as a whole, light havingcontrast according to image signals is output from the liquid crystaldevice.

In order to prevent leakage of the image signals maintained, for each ofthe liquid crystal capacitors formed between the pixel electrodes 9 andthe opposing electrodes 21 (see FIG. 2), a storage capacitor 70 iselectrically connected in parallel.

1-3: Specific Configuration of Liquid Crystal Device

Next, a specific configuration of the pixels of the liquid crystaldevice 1 will be described with reference to FIGS. 4 to 7. FIG. 4 is aplan view schematically showing a position relationship, such aselectrodes and wiring which are disposed to perform the electro-opticaloperation, in the image display region 10 a of the liquid crystal device1 according to the embodiment. FIGS. 5 and 6 are plan views showing indetail the configuration of a portion of the image display region 10 a.FIGS. 5 and 6 shows different layers on the TFT-array substrate 10 in asolid line, and show a plan structure in the region slightly wider FIG.4. FIG. 7 is a cross-sectional view taken along a line VII-VII in FIGS.4 to 6. In this instance, in FIGS. 4 to 7, each of the layers and eachof the members are shown in different scales in order to illustrate therespective layers and the respective members in a perceptible size onthe figure.

In FIG. 4, on the TFT array substrate 10, the scanning lines 11 servingas a “first light shielding film” of the invention and the data lines 6serving as a “second light shielding film” of the invention are extendedin an X direction and a Y direction, respectively. The TFT 30 (i.e., asemiconductor layer 30 a and a gate electrode 30 b) is formed to overlapthe scanning line 11 at the region adjacent to the intersection of thedata line 6 and the scanning line 11. The scanning line 11 is made of alight shielding conductive material, for example, W (tungsten), Ti(titanium), TiN (titanium nitride) or the like, and is formed to have awidth wider than the semiconductor layer 30 a so as to include thesemiconductor layer 30 a of the TFT 30. As described above, since thescanning line 11 is placed at a layer side lower than the semiconductorlayer 30 a, the scanning line 11 is formed to have a width wider thanthe semiconductor layer 30 a of the TFT 30, thereby almost or completelyshielding the channel region 30 b of the TFT 30 from the return lightsuch as back-side reflection in the TFT-array substrate 10 or the lightproduced from another liquid crystal device, such as a projector of aduplicated plate type and penetrating a synthesis optical system. As aresult, at the time of operation of the liquid crystal device 1, lightleakage current can be reduced in the TFT 30, thereby enhancing acontrast ratio and thus enabling an image of high quality to display.

Since the scanning line 11 has a light shielding property, the scanningline defines a non-opening region in the image display region 10 atogether with the data line 6. In this instance, each of the scanninglines 11 and the data lines 6 may be formed in such a way that an edgeof each scanning lines 11 and the data lines 6 does not define thenon-opening region. In other words, each of the scanning lines 11 andthe data lines 6 may be formed in the non-opening region defined byother light shielding film which is formed on the TFT-array substrate10.

The TFT 30 includes the semiconductor layer 30 a and the gate electrode30 b. The semiconductor layer 30 a is configured to have a source region30 a 1, a channel region 30 a 2, and a drain region 30 a 3. Here, at aninterface between the channel region 30 a 2 and the source region 30 a 1or the channel region 30 a 2 and the drain region 30 a 3, an LDD(Lightly Doped Drain) region may be formed.

The gate electrode 30 b is formed in the region which overlaps thechannel region of the semiconductor layer 30 a, when seen in a plan viewover the TFT-array substrate 10, with a gate insulation film beinginterposed therebetween. Although not shown in FIG. 4, the gateelectrode 30 b is electrically connected to the scanning line 11 whichis placed at a lower layer, via a contact hole 34. If a scanning signalis applied to the gate electrode 30 b, the gate electrode controlsON/OFF of the TFT 30.

Since the data line 6 is placed on the TFT 30 and thus overlaps the TFT30, the data line can shield the light from the TFT 30 at the upperside. The data line 6 is electrically connected to the contact hole 31which is an example of an “input terminal” of the invention. The dataline 6 is electrically connected to, for example, the source region 30 a1 (see FIG. 7) of the TFT 30, and constitutes a portion of the data linesupplying the image signal to the TFT 30.

Meanwhile, the drain region 30 a 3 is electrically connected to thepixel electrode 9 via a contact hole 32 and a relay layer 7 whichconstitute an example of an “output terminal” of the invention and acontact hole 33 which is an example of a “connection portion” of theinvention (see FIG. 7).

In FIG. 5, a capacitor electrode 71 which is an example of a“transparent conductive film” of the invention is made of, for example,a transparent conductive material such as ITO, and constitutes a pair ofcapacitor electrodes together with the pixel electrode 9 in a storagecapacitor 70. The capacitor electrode 71 overlaps the substantiallywhole portion of the image display region 10 a, and is extended towardsthe upper layer side of the data line 6 in an opening region throughwhich the light penetrates.

Each of the data lines 6 and the scanning lines 11 is extended in the Ydirection and the X direction, respectively. Each of the pixels isdivided by the data lines 6 and the scanning lines 11. The capacitorelectrode 71 is formed on the layer side lower than the pixel electrode9 (not shown in FIG. 5), and an aperture portion 5 a every pixel. In theaperture portion 5 a, the contact hole 33 which electrically connectsthe pixel electrode 9 and the drain region 30 a 3 (see FIG. 7) is formedin a vertical direction on the figure, that is, along a thicknessdirection of the TFT-array substrate 10. Consequently, according to thecontact hole 33, the capacitor electrode 71 formed on the lower layerside of the pixel electrode 9 is not electrically short-circuited, andcan supply an image signal potential output from the drain region 30 a 3to the pixel electrode 9. As a result, even though the capacitorelectrode 71 is provided on the lower layer side of the pixel electrode9, it is able to drive the pixel electrode 9 On/OFF, so that the liquidcrystal device 1 having very effective wiring layout can be implemented.

In FIG. 6, the pixel electrode 9 is formed in an island shape for everypixel. In this embodiment, each pixel is divided in a matrix shape bythe data lines 6 and the scanning lines 11. As shown by a dotted line 9a in FIG. 4, the pixel electrode 9 is formed to partially overlap thedata line 6 and the scanning line 11 in the respective pixels, when seenin a plan view on the TFT-array substrate 10. The storage capacitor 70is formed in a region in which the capacitor electrode 71 and the pixelelectrode 9 overlap each other.

In FIG. 7, on the TFT-array substrate 10, insulation films 12, 13, 14and 15 and a dielectric film 72 are formed. Each of the scanning lines11, the TFT 30, the data lines 6, the capacitor electrodes 71 and thepixel electrodes 9 is formed on the TFT-array substrate 10, theinsulation film 12, the insulation film 14, the insulation film 15 andthe dielectric film 72, respectively.

The dielectric film 72 is a transparent film formed on the capacitorelectrode 71 in the opened region through which the light penetrates.The dielectric film 72 is made of alumina having a dielectric constantrelatively higher than other dielectric films, and forms the storagecapacitor 70 together with the capacitor electrode 71 and the pixelelectrode 9 in the opening region. Since alumina has a dielectricconstant relatively higher than other dielectric material, it is able toincrease a settable capacitance value in the case in which the size ofthe storage capacitor 70 is constant. In this instance, it is preferableto make a film thickness of the dielectric film 72 thin so as toincrease the capacitance value of the storage capacitor 70.

Since each of the storage capacitors 70 includes the transparentcapacitor electrode 71, the dielectric film 72 and the pixel electrode9, the opening region may not be narrowed, and an opening ratio which isa ratio of the opening region occupying the pixel is not lowered.Further, according to the storage capacitor 70, since the storagecapacitor 70 is formed in the opening region, it is able to increase thecapacitance value thereof as compared with the case in which the storagecapacitor is formed only in the non-opening region.

Consequently, according to the liquid crystal device 1, the capacitancevalue of the storage capacitor 70 may be increased, and the size of theopening region may be enlarged, thereby enhancing the displayperformance of the liquid crystal device 1.

Modified Example

Next, a modified example of the liquid crystal device 1 according tothis embodiment will be described with reference to FIG. 8. FIG. 8 is across-sectional view showing the configuration of the modified exampleof the liquid crystal device according to this embodiment, and is apartial cross-sectional view taken by cutting the liquid crystal deviceaccording to the modified example in the cross section corresponding toFIG. 7. In this instance, common parts to the liquid crystal device 1are designated by same reference numerals, and the detailed descriptionthereof will be omitted.

In FIG. 8, the liquid crystal device according to this embodiment isdifferent from the above-described liquid crystal device 1, except for arelay layer 7 a, data lines 6 a, contact holes 33 a, 34, 35 and 36,insulation films 17 and 18 and a dielectric film 72 a.

The dielectric film 72 a is made of alumina, similar to the dielectricfilm 72, and constitutes the storage capacitor 70 together with thecapacitor electrode 71 and the pixel electrode 9. In this instance, inthe non-opening region constituting a portion of the image displayregion 10 a, the insulation film 18 is extended between the pixelelectrode 9 and the capacitor electrode 71. The pixel electrode 9 iselectrically connected to the drain region 30 a 3 via the contact holes36, 35 and 33 a, the relay layer 7 a and the contact hole 32. Accordingto the liquid crystal device of this embodiment, the capacitance valueof the storage capacitor 70 is increased, and the size of the openingregion is enlarged, thereby enhancing the display performance of theliquid crystal device 1, similar to the above-described liquid crystaldevice 1.

The data line 6 a is an example of a “second light shielding film” ofthe invention, and is formed on the insulation film 17. The data line 6a is electrically connected to the contact hole 31 via the contact hole34.

The relay layer 7 a and the contact hole 32 constitute an example of an“output terminal” of the invention. The relay layer 7 a is extendedtowards the upper layer side of the TFT 30 to overlap the TFT 30 toshield the TFT 30 from the light together with the data line 6 a andelectrically relay the TFT 30 and the pixel electrode 9.

Consequently, according to the liquid crystal device, it is able toshield the TFT 30 from the light at both sides of the data line 6 a andthe relay layer 7 a. Therefore, it is able to eliminate light leakagecurrent produced in the TFT 30, at the time of operation of the liquidcrystal device.

Second Embodiment

Next, a liquid crystal device according to the second embodiment will bedescribed with reference to FIGS. 9 to 11. In this instance, the secondembodiment is substantially identical to the first embodiment, exceptfor some configurations. For this reason, in the second embodiment, theportions different from those of the first embodiment will be describedin detail, and the same portions will be not described herein.

FIGS. 9 and 10 are plan views transparently showing a positionalrelationship of the respective layers constituting the liquid crystaldevice according to the second embodiment. FIG. 11 is a cross-sectionalview showing a laminate structure of the liquid crystal device accordingto the second embodiment. In this instance, in FIG. 9, each layer lowerthan the relay layer 91 and 92 is shown, and in FIG. 10, each layerhigher than the relay layer 91 and 92 is shown. Further, in FIGS. 9 to11, each of the layers and each of the members are shown in differentscales in order to illustrate the respective layers and the respectivemembers in a perceptible size on the figure. FIG. 11 shows a crosssection taken along a line XI-XI in FIGS. 9 and 10, but since the scaleof the respective layers and the respective members are different, thereare portion which do not absolutely correspond to the line XI-XI.

In FIGS. 9 and 11, on the TFT-array substrate 10, the scanning lines 11are disposed along an X direction, and the TFT 30 having thesemiconductor layer 30 a and the gate electrode 30 b is disposed on anupper layer of the scanning lines 11, with an underlying insulation film12 being interposed therebetween.

The scanning line 11 is made of a light shielding conductive material,for example, W (tungsten), Ti (titanium), TiN (titanium nitride) or thelike, and is configured to include the semiconductor layer 30 a whenseen in a plan view on the TFT-array substrate 10. More specifically, asshown in FIG. 10, the scanning line 11 has a protrusion portionprotruding along the semiconductor layer 30 a in the Y direction. Sincethe scanning line 11 is placed on a layer lower than the semiconductorlayer 30 a and has the above-described protrusion portion, theprotrusion portion can almost or completely shield the channel region 30b of the TFT 30 from the return light such as back-side reflection inthe TFT-array substrate 10 or the light produced from other liquidcrystal device, such as a projector of a duplicated plate type andpenetrating a synthesis optical system. As a result, at the time ofoperation of the liquid crystal device, light leakage current can bereduced in the TFT 30, thereby enhancing a contrast ratio and thusenabling an image of high quality to display.

The TFT 30 includes the semiconductor layer 30 a and the gate electrode30 b. The semiconductor layer 30 a is configured to have a source region30 a 1, a channel region 30 a 2, and a drain region 30 a 3. Here, at aninterface between the channel region 30 a 2 and the source region 30 a 1or the channel region 30 a 2 and the drain region 30 a 3, an LDD(Lightly Doped Drain) region may be formed.

The gate electrode 30 b is formed on the upper layer side of thesemiconductor layer 30 a in the region which overlaps the channel region30 a 2 of the semiconductor layer 30 a, at plane view over the TFT-arraysubstrate 10, with a gate insulation film 13 being interposedtherebetween. The gate insulation electrode 30 b is made of, forexample, conductive polysilicon, and is electrically connected to thescanning line 11 disposed on a lower layer side via the contact holes 34a and 34 b.

The source region 30 a 1 of the TFT 30 is electrically connected to therelay layer 91 formed on a first interlayer dielectric 14 via thecontact hole 31. The drain region 30 a 3 is electrically connected tothe relay layer 92 formed as the same layer as the relay layer 91 viathe contact hole 32. The relay layer 92 is an example of a “third relaylayer” of the invention.

In FIGS. 10 and 11, the relay layer 91 is electrically connected to thedata lines 6 formed on a second interlayer dielectric 15 via the contacthole 34. The data line 6 is an example of a “light shielding layer” ofthe invention. The relay layer 92 is electrically connected to the relaylayer 7 formed as the same layer as the data lines 6 via the contacthole 34. The data line 6 is an example of a “second light shieldinglayer” of the invention, and the relay layer 7 is an example of a“second relay layer” of the invention.

The relay layer 7 is electrically connected to the relay layer 75 formedon the same layer as the capacitor electrode 71, which will be describedbelow, via the contact hole 36. In this instance, the relay layer 75 isan example of “a first relay layer” of the invention. The relay layer 75is electrically connected to the pixel electrode 9 via the contact hole37. That is, the drain region 30 a 3 of the TFT 30 and the pixelelectrode 9 are electrically relay-connected to each other via the relaylayer 92, the relay layer 7 and the relay layer 75 in this order.

On the data lines 6 and the relay layer 7, the storage capacitor 70 isformed, with a third interlayer dielectric 16 being interposedtherebetween. Since the storage capacitor 70 is electrically connectedin parallel to the liquid crystal capacitor, it is able to maintain thevoltage of the pixel electrode 9, for example, by a time three-digitslonger than the time for which the image signal is applied. Therefore, asustain characteristic of the liquid crystal element is improved, andthus the liquid crystal device having high contrast ratio can beimplemented.

The capacitor electrode 71 is an example of a “transparent conductivefilm” of the invention, and serves as one electrode of the storagecapacitor 70 which is electrically connected in parallel to the liquidcrystal capacitance. The capacitor electrode 71 is electricallyconnected to a capacitance wiring 300, and thus is maintained in a fixedpotential. The capacitor electrode 71 is made of, for example, atransparent electrode such as ITO. For this reason, even though thecapacitor electrode 71 is formed to overlap the image display region 10a including the opening region, a light transmittance in the openingregion is not almost or never decreased in practice. The capacitorelectrode 71 is formed to enclose the relay layer 75 which is formed inan island shape. In other words, the relay layer 75 is formed inside theaperture portion of the capacitor electrode 71. The relay layer 92 has abody portion overlapping along the scanning line 11, and a protrusionportion disposed to cover the drain region a3 from a portion of at leastchannel region of the TFT 30 which is vertically disposed. The relaylayer 7 has an island shape overlapping along the body portion of therelay layer 92. Further, the relay layer 75 is installed in such a waythat its vertical width is wider than the relay layer 7 so as toprotrude from the relay layer 92 of the island shape towards the pixelelectrode side. The aperture portion of the capacitor electrode 71 isopened so as to provide the contact hole 36 which is connected to therelay layer 7 and the relay layer 75, and the contact hole 37 which isconnected to the relay layer 75 and the pixel electrode 9. The relaylayer 7 is made of the same light shielding material as the data line,and is provided between a pixel and a pixel. The relay layer 75 is madeof the same transparent material as the capacitor electrode 71, and eventhough it protrudes toward the pixel electrode side, the opening ratioof the image display region 10 a is not deteriorated. Since the apertureportion of the capacitor electrode 71 is provided across two pixels of avertical direction, by providing the transparent relay layer 75 insidethe aperture portion thereof, it is able to ensure a margin forproviding the relay layer 7 of a light shielding material and thecontact hole 36 at the position between the pixel electrodes, andsimultaneously providing the contact hole 36 at the position overlappingthe relay layer 7.

The dielectric film 72 is formed on the capacitor electrode 71. Thedielectric film 72 is formed as a solid to cover the capacitor electrode71. In this instance, since the dielectric film 72 is made of nitridesilicon which is a transparent dielectric material, even though thedielectric layer 72 is widely formed on the image display region 10 aincluding the opening region, the light transmittance in the openingregion is not almost or never decreased in practice. Meanwhile, it ispreferable to make a film thickness of the dielectric film 72 thin so asto increase the capacitance value of the storage capacitor 70.

Further, a capacitor separation film 80 for separating the storagecapacitor 70 between the pixels is provided on the capacitor electrode71. The capacitance value of the storage capacitor 70 can be adjusted byincreasing or decreasing an area of the capacitor separation film 80.More specifically, by providing the capacitor separation film 80, thestorage capacitor 70 is not formed at the portion in which the capacitorelectrode 71 is not provided opposite to the pixel electrode 9 acrossthe dielectric film 72. As shown in FIG. 10, the capacitor separationfilm 80 has a capacitor separation film aperture portion which is formedin an approximately H-shape so as to avoid the aperture portion of thecapacitor electrode 71 over the pixel adjacent to the capacitorseparation film 80. The capacitor electrode 71 and the pixel electrode 9are placed opposite to each other to form the storage capacitor 70 inaccordance with the shape of the aperture portion of the capacitorseparation film. That is, the aperture portion of the capacitorseparation film is provided between the data lines 6 adjacent to theaperture portion of the capacitor electrode which is provided betweenthe adjacent data lines 6, to form the storage capacitor, so that aplanar area of the storage capacitor region is seized in the pixelelectrode 9 as much as possible. Here, in the case in which thecapacitance value of the storage capacitor 70 is low, since the time forsustaining the image signal is short, the quality of the display imageis not much improved. Meanwhile, in the case in which the capacitancevalue of the storage capacitor 70 is high, since the image signal can besustained for a long time, the improvement in the quality of the displayimage is expected, but a supply circuit or wiring for the image signalbecomes bigger. For this reason, the capacitance value of the storagecapacitor 70 is adjusted to a desired value in the actual liquid crystalapparatus.

On the capacitor separation film 80, the pixel electrode 9 is formed. Asshown in FIG. 10, the pixel electrode 9 is formed in an island shape forevery pixel which is divided in the matrix shape by the data lines 6 andthe scanning lines 11. In this instance, although not shown herein, onthe pixel electrode 9, an arrangement film 16 is formed to define anorientation state of liquid crystal molecules contained in the liquidcrystal layer 50 (see FIG. 2).

As described above, according to the liquid crystal device of the secondembodiment, the capacitance value of the storage capacitor 70 isincreased, and the size of the opening region is enlarged, therebyenhancing the display performance of the liquid crystal device 1,similar to the first embodiment.

2: Electronic Apparatus

Next, an example, in which the liquid crystal device described above isapplied to a projector which is an example of the electronic apparatus,as a light valve will be described with reference to FIG. 12. FIG. 12 isa plan view showing an example of the configuration of the projector.

Referring to FIG. 12, inside a projector 1100, a lamp unit 1102 having awhite light source, such as a halogen lamp, is provided. Light emittedfrom the lamp unit 1102 is separated into components of the threeprimary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108disposed in a light guide 1104, and the R, B, and G components enterliquid crystal panels 1110R, 1110B, and 1110G corresponding to eachprimary color, which serve as light valves, respectively.

The configurations of the liquid crystal panels 1110R, 1110B, and 1110Gare equal to the liquid crystal device described above, and are drivenrespectively by primary-color signals of R, B, and G supplied from animage-signal processing circuit. Light components that have beenmodulated by these liquid crystal panels 1110R, 1110B, and 1110G enter adichroic prism 1112 from three directions. The dichroic prism 1112causes the R and B light components to refract by an angle of 90 degreeswhile causing the G light component to go straight. Thus, by combiningimages of the respective colors, a color image is projected onto ascreen or the like via a projection lens 1114.

Considering the respective images displayed by the liquid crystal panels1110R, 1110B, and 1110G, the image displayed by the liquid crystal panel1110G has to be flipped left-for-right with respect to the imagesdisplayed by the liquid crystal panels 111OR and 1110B.

Since the liquid crystal panels 1110R, 1110B, and 1110G receive lightcomponents of the primary colors of R, B, and G via the dichroic mirrors1108, respectively, color filters need not be provided.

Without limitation to the electronic apparatus described with referenceto FIG. 12, the liquid crystal device can be used in various otherelectronic apparatuses, such as mobile personal computers, cellularphones, liquid crystal television sets, view-finders ormonitor-direct-viewing video tape recorders, car navigation sets,pagers, electronic notebooks, electronic calculators, word processors,workstations, video phones, point-of-sale (POS) terminals, orapparatuses having touch panels.

In addition, without limitation to the liquid crystal device describedin each embodiment, the invention can be applied to liquid crystal onsilicon (LCOS), a plasma display panel (PDP), a field emission displayor surface-conductive electron emitter display (FED or SED), an organicEL display, a digital micromirror device (DMD), an electrophoresisdevice, and so forth.

The invention is not limited to the embodiments described above, andvarious modifications can be made without departing from the gist orspirit of the invention as understood from the claims and thespecification as a whole. Electro-optical devices involving suchmodifications and electronic apparatuses including such electro-opticaldevices also fall within the scope of the invention.

The entire disclosure of Japanese Patent Application Nos: 2009-000277,filed Jan. 5, 2009, 2009259898, filed Nov. 13, 2009 are expresslyincorporated by reference herein.

What is claimed is:
 1. An electro-optical device comprising: asubstrate; a scanning line disposed over the substrate, the scanningline extends along a first direction; a semiconductor layer disposedover the scanning line, the semiconductor layer overlapped with thescanning line; a data line disposed over the semiconductor layer, thedata line is electrically connected to the semiconductor layer, the dataline extends along a second direction that intersects the firstdirection; a relay layer disposed over the semiconductor layer, therelay layer electrically connected to the semiconductor layer; acapacitor electrode disposed over the data line, the capacitor electrodehas an aperture portion; a pixel electrode disposed over the capacitorelectrode; and a dielectric film disposed between the capacitorelectrode and the pixel electrode, the dielectric film constitutes astorage capacitor together with the capacitor electrode and the pixelelectrode, wherein each of the scanning line, the data line, and therelay layer are made of a light shielding material, each of thecapacitor electrode, the dielectric film, and the pixel electrode aremade of a transparent material, the capacitor electrode is overlappedwith the pixel electrode in an opening region through which lightpenetrates, the semiconductor layer extends along the first direction,the relay layer protrudes to the opening region in the second direction,and the relay layer electrically connected to the pixel electrode via acontact hole disposed in the aperture portion of the capacitorelectrode.
 2. The electro-optical device according to claim 1, whereinthe data line and the relay layer are disposed as a same layer.
 3. Theelectro-optical device according to claim 1, wherein the pixel electrodeis connected directly to the relay layer.
 4. The electro-optical deviceaccording to claim 1, wherein the contact hole is disposed so as not tooverlap with the scanning line.
 5. An electronic apparatus comprisingthe electro-optical device according to claim 1.